---
id: customize_attachment_picker_modal
title: Attachment Picker Modal
---

Customizing the Attachment Picker Modal

### Introduction

The Attachment Picker is a modal that allows users to select attachments from their device.
It is generally used when a user taps the attachment button in the [StreamMessageInput](../../03-stream_chat_flutter/stream_message_input.mdx).

By default, the Attachment Picker provides multiple picker options as per the platform.
- For example, on Mobile, the default options are Camera, Gallery, File, and Video.
- On Web and Desktop, the default options are Image, Video and File.

### Customizing the Attachment Picker Modal

The Attachment Picker Modal can be customized by passing the different values to the `showStreamAttachmentPickerModalBottomSheet` function.

#### Initial Attachments

The initial attachments can be passed to the Attachment Picker Modal in two ways.

 * By passing the `initialAttachments` parameter.

 ```dart
 StreamMessageInputController _messageInputController =
       StreamMessageInputController();
 ...
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   initialAttachments: [
     // Pass the initial attachments to the modal here if any are available already (optional)
     ..._messageInputController.attachments,
   ],
 );
 ```

 * By creating a new instance of the `AttachmentPickerModalController` and passing it to the `controller` parameter.

 ```dart
 final attachmentPickerController = StreamAttachmentPickerController(
    initialAttachments: [
      // Pass the initial attachments to the modal here if any are available already (optional)
      ...messageInputController.attachments,
    ],

    // The `maxAttachmentSize` and `maxAttachmentCount` can also be set while creating a controller.
    maxAttachmentSize: 10 * 1024 * 1024, // 10 MB
    maxAttachmentCount: 10, // 10 attachments
 );

 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   controller: attachmentPickerController,
 );
 ```

#### Custom Attachment Picker Options

The Attachment Picker Modal provides a default set of options as per the platform.
However, you can also customize the options by passing the `customOptions` parameter.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   customOptions: [
     // Pass the custom attachment picker options here
     AttachmentPickerOption(
       icon: const Icon(Icons.audiotrack),
       supportedTypes: [AttachmentPickerType.audios],
       optionViewBuilder: (context, attachmentPickerController) {
         return AudioPicker(
           onAudioPicked: (audio) async {
             await attachmentPickerController.addAttachment(audio);
             return Navigator.pop(context, attachmentPickerController.value);
           },
         );
       },
     ),
   ],
 );
 ```

#### Attachment thumbnail size

The size of the attachment thumbnail item shown in the gallery picker can be defined by passing the `attachmentThumbnailSize` parameter.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   attachmentThumbnailSize: const ThumbnailSize.square(600),
 );
 ```

#### Attachment thumbnail format

The format of the attachment thumbnail item shown in the gallery picker can be defined by passing the `attachmentThumbnailFormat` parameter.

Possible values are `ThumbnailFormat.jpeg` and `ThumbnailFormat.png`.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   attachmentThumbnailFormat: ThumbnailFormat.jpeg,
 );
 ```

#### Attachment thumbnail quality

The quality of the attachment thumbnail item shown in the gallery picker can be defined by passing the `attachmentThumbnailQuality` parameter.

Possible values are between 0 and 100.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   attachmentThumbnailQuality: 70,
 );
 ```

#### Attachment thumbnail scale

The scale of the attachment thumbnail item shown in the gallery picker can be defined by passing the `attachmentThumbnailScale` parameter.

For example, if this is 2, it means that there are four image pixels for every one logical pixel, and the image's actual width and height are
double the height and width that should be used when painting the image.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   attachmentThumbnailScale: 2,
 );
 ```

#### Additional modal bottom sheet parameters

The `showStreamAttachmentPickerModalBottomSheet` function also accepts the parameters that are available in the `showModalBottomSheet` function.

 ```dart
 showStreamAttachmentPickerModalBottomSheet(
   context: context,
   isScrollControlled: true,
   backgroundColor: Colors.transparent,
   useRootNavigator: true,
   elevation: 4,
   isDismissible: true,
   clipBehavior: Clip.antiAlias,
   barrierColor: Colors.black.withOpacity(0.5),
   constraints: const BoxConstraints(
     maxHeight: 500,
     maxWidth: 500,
   ),
   shape: RoundedRectangleBorder(
     borderRadius: BorderRadius.vertical(
       top: Radius.circular(16),
     ),
   ),
 );
 ```